Pub Date : 2020-05-26DOI: 10.1299/transjsme.20-00001
I. Tanabe, Takehiro Suzuki, Satoshi Takahashi
Recently many products with high quality, high dignity, high confidence, multipurpose and originality in innovation technology were developed. Now everyone still desires the higher properties for several products. Therefore, in this research, the material optimization technology for small structures was developed and evaluated. The some small structures were desired for miniaturizing, weight saving and energy saving in the products. The concept of “material optimization” is a new and general idea. This material is the composite type. The material optimization technology regarding Young’s modulus, density, coefficient of linear expansion, specific heat and thermal conductivity was spread in this research. The calculation models for the properties were firstly cleared. The manufacturing method for small structures with the desired properties was also developed. Then the small structure with the material optimization were calculated through a newly developed program and were made by the new manufacturing method. The small structure with the material optimization was manufactured and evaluated. It is concluded from the results that the technology was very effective and useful for development of a new composite material with several hybrid properties.
{"title":"Development of material optimization technology for small structure","authors":"I. Tanabe, Takehiro Suzuki, Satoshi Takahashi","doi":"10.1299/transjsme.20-00001","DOIUrl":"https://doi.org/10.1299/transjsme.20-00001","url":null,"abstract":"Recently many products with high quality, high dignity, high confidence, multipurpose and originality in innovation technology were developed. Now everyone still desires the higher properties for several products. Therefore, in this research, the material optimization technology for small structures was developed and evaluated. The some small structures were desired for miniaturizing, weight saving and energy saving in the products. The concept of “material optimization” is a new and general idea. This material is the composite type. The material optimization technology regarding Young’s modulus, density, coefficient of linear expansion, specific heat and thermal conductivity was spread in this research. The calculation models for the properties were firstly cleared. The manufacturing method for small structures with the desired properties was also developed. Then the small structure with the material optimization were calculated through a newly developed program and were made by the new manufacturing method. The small structure with the material optimization was manufactured and evaluated. It is concluded from the results that the technology was very effective and useful for development of a new composite material with several hybrid properties.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"2 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141202847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1299/transjsme.19-00226
M. Michihata, Y. Kobayashi, Bohuai Chu, K. Takamasu, S. Takahashi
A sphere is a frequently used shape as a reference of calibration for 3-dimensional measurement instruments because of its isotropic shape. It is demanded to measure the diameter of the reference sphere with high accuracy. For micro-scale 3-dimentional metrology, size of the reference sphere is from several millimeters to a few tens of micrometers. These spheres have to be measured with accuracy of better than 10 nm. Therefore, we have proposed the new measurement method of a microsphere based on whispering gallery mode resonances. One of the key points to the proposed method is to measure the whispering gallery mode resonant wavelength accurately and precisely. In this paper, the measurement system for WGM was developed. Using this system, the measurement repeatability of WGM resonant wavelength better than 0.2 pm was achieved.
{"title":"Development of measuring system of whispering gallery mode resonances for evaluating a diameter of microsphere","authors":"M. Michihata, Y. Kobayashi, Bohuai Chu, K. Takamasu, S. Takahashi","doi":"10.1299/transjsme.19-00226","DOIUrl":"https://doi.org/10.1299/transjsme.19-00226","url":null,"abstract":"A sphere is a frequently used shape as a reference of calibration for 3-dimensional measurement instruments because of its isotropic shape. It is demanded to measure the diameter of the reference sphere with high accuracy. For micro-scale 3-dimentional metrology, size of the reference sphere is from several millimeters to a few tens of micrometers. These spheres have to be measured with accuracy of better than 10 nm. Therefore, we have proposed the new measurement method of a microsphere based on whispering gallery mode resonances. One of the key points to the proposed method is to measure the whispering gallery mode resonant wavelength accurately and precisely. In this paper, the measurement system for WGM was developed. Using this system, the measurement repeatability of WGM resonant wavelength better than 0.2 pm was achieved.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123667297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-06-21DOI: 10.1299/TRANSJSME.19-00059
J. Hasegawa, N. Kubota
From worldwide statistical data of whiplash injuries in the rear-end impact accidents, females have been found to be at a higher risk than males and the reason for the same is an ongoing research topic. First, we created finite element model of the head and neck of a 50th %ile Japanese adult female (JAF50) by scaling an existing 50th %ile (JAM50) male model. The activity level of neck muscles before a rear-end impact was determined using the L36 of DOE method, which held a neutral posture of the head with the relaxed muscles under 1G condition. Subsequently, the head and neck behaviors of both the models were validated using the volunteer's rear-end impact test data. Comparing both the results using a new index (S θmax), which measured the S-shape deformation of the neck during rear-end impacts, the model results were found to have the same trends as that of the volunteer's test data. JAF50 had a higher (S θmax) value than JAM50, which means that a female neck undergoes larger S-shaped mode than a male. This index value difference between the genders was due to the difference in their muscle forces while maintaining a neutral posture of the head. This difference in the muscle forces, however, was not proportional to only the head mass ratio of the two genders. As a result of the investigation of the underlying reason, the neck muscle force ratio of each gender at the neutral position was roughly related to mass ratio × neck column cross-sectional area ratio × neck length ratio. If the ratio (female to male) of neck circumferences was 3: 4, the female muscle force could be nearly twice less than that of a male. We also estimated the muscle activity for each gender assuming the same (S θmax) = 15 ° at the rear-end impact of Δ V = 5 km/h. It was found that a female's muscle activity is about twice that of a males for the same rear-end impact conditions.
从世界范围内的追尾碰撞事故中颈部扭伤的统计数据来看，女性的风险高于男性，其原因是一个正在进行的研究课题。首先，我们通过缩放现有的50%成年男性模型(JAM50)，创建了50%成年日本女性(JAF50)的头颈有限元模型。追尾前颈部肌肉活动水平采用DOE法L36，在1G条件下保持头部中性姿势，肌肉放松。随后，使用志愿者的追尾碰撞试验数据验证了两种模型的头部和颈部行为。使用一个新的指数(S θmax)来比较这两个结果，该指数测量了追尾碰撞时颈部的S形变形，发现模型结果与志愿者的测试数据具有相同的趋势。JAF50的(S θmax)值高于JAM50，说明女性颈部比男性经历更大的S型模式。男女之间的指数值差异是由于他们在保持头部中立姿势时肌肉力量的差异。然而，这种肌肉力量的差异并不仅仅与两性的头部质量比成正比。通过对其深层原因的调查，得出中性位时男女颈部肌力比大致与质量比×颈柱截面积比×颈长比相关。如果颈部周长(女性与男性)的比例是3:4，那么女性的肌肉力量可能比男性少近两倍。我们还估计了在Δ V = 5 km/h的追尾冲击下，假设相同(S θmax) = 15°，每个性别的肌肉活动。研究发现，在相同的追尾条件下，女性的肌肉活动大约是男性的两倍。
{"title":"A study of whiplash injury occurrence mechanisms using human head-neck finite element model (Analysis of factors on the gender difference)","authors":"J. Hasegawa, N. Kubota","doi":"10.1299/TRANSJSME.19-00059","DOIUrl":"https://doi.org/10.1299/TRANSJSME.19-00059","url":null,"abstract":"From worldwide statistical data of whiplash injuries in the rear-end impact accidents, females have been found to be at a higher risk than males and the reason for the same is an ongoing research topic. First, we created finite element model of the head and neck of a 50th %ile Japanese adult female (JAF50) by scaling an existing 50th %ile (JAM50) male model. The activity level of neck muscles before a rear-end impact was determined using the L36 of DOE method, which held a neutral posture of the head with the relaxed muscles under 1G condition. Subsequently, the head and neck behaviors of both the models were validated using the volunteer's rear-end impact test data. Comparing both the results using a new index (S θmax), which measured the S-shape deformation of the neck during rear-end impacts, the model results were found to have the same trends as that of the volunteer's test data. JAF50 had a higher (S θmax) value than JAM50, which means that a female neck undergoes larger S-shaped mode than a male. This index value difference between the genders was due to the difference in their muscle forces while maintaining a neutral posture of the head. This difference in the muscle forces, however, was not proportional to only the head mass ratio of the two genders. As a result of the investigation of the underlying reason, the neck muscle force ratio of each gender at the neutral position was roughly related to mass ratio × neck column cross-sectional area ratio × neck length ratio. If the ratio (female to male) of neck circumferences was 3: 4, the female muscle force could be nearly twice less than that of a male. We also estimated the muscle activity for each gender assuming the same (S θmax) = 15 ° at the rear-end impact of Δ V = 5 km/h. It was found that a female's muscle activity is about twice that of a males for the same rear-end impact conditions.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"211 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116397050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-04-22DOI: 10.1299/TRANSJSME.18-00467
T. Funada
A bifilar suspension pendulum, a uniform density bar suspended at its two points by two strings of same length from an upper horizontal plane, may swing in two vertical planes or make torsional oscillation about a vertical axis. The free oscillation periods measured in the three modes match well the normal modes derived from linear theory due to the pendulum configuration. These modes are linearly independent of each other, but it is possible to make nonlinear coupling between those as various types of internal resonance. For each mode, a common equation of inertia type shows to give nonlinear hardening/softening. Swing mode 1 has softening as in the simple pendulum, but Swinging-bar mode 2 makes softening/hardening mainly depending on the configuration. Rotational oscillation mode 3 also makes softening/hardening with changing the moment of inertia and the configuration. These are shown analytically and numerically by methods of singular perturbation and numerical computations, prior to an analysis of the internal resonances in a forthcoming paper.
{"title":"A nonlinear analysis on the three oscillation modes of a bifilar suspension pendulum (1) (Formulation of nonlinear oscillation problem and primary resonance analysis of one degree of freedom nonlinear inertia type forced damping systems)","authors":"T. Funada","doi":"10.1299/TRANSJSME.18-00467","DOIUrl":"https://doi.org/10.1299/TRANSJSME.18-00467","url":null,"abstract":"A bifilar suspension pendulum, a uniform density bar suspended at its two points by two strings of same length from an upper horizontal plane, may swing in two vertical planes or make torsional oscillation about a vertical axis. The free oscillation periods measured in the three modes match well the normal modes derived from linear theory due to the pendulum configuration. These modes are linearly independent of each other, but it is possible to make nonlinear coupling between those as various types of internal resonance. For each mode, a common equation of inertia type shows to give nonlinear hardening/softening. Swing mode 1 has softening as in the simple pendulum, but Swinging-bar mode 2 makes softening/hardening mainly depending on the configuration. Rotational oscillation mode 3 also makes softening/hardening with changing the moment of inertia and the configuration. These are shown analytically and numerically by methods of singular perturbation and numerical computations, prior to an analysis of the internal resonances in a forthcoming paper.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124914852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1299/TRANSJSME.19-00029
K. Okumo, Y. Takahashi, Tae Sung Kim, Hidefumi Nikawa, A. Hosoi, H. Kawada
Carbon nanotubes (CNT) have remarkable mechanical properties and low density. Since length of the CNT is limited, CNT yarn is regarded as a reinforced fiber of carbon fiber reinforced plastics. However, the CNT yarn does not have remarkable mechanical properties such as the individual CNT. The most popular way for improving the mechanical properties of the CNT yarn is to make composites with polymer such as polyvinyl alcohol or polyimide. If some functional groups such as carboxyl groups are introduced on the surface of CNTs, interaction between the CNTs and the polymer is improved and high mechanical properties will be obtained. In this study, untwisted CNT yarns were prepared by drawing vertical aligned CNTs through a die and functionalized with mixed acid. Mixed acid introduced not only the functional groups but also defects on the surface of CNTs. For reducing the defects, the CNT yarn was graphitized at a temperature of 2800°C before the mixed acid treatment. By the graphitization treatment, crystallinity of the CNT yarn was improved and amorphous carbon was removed. As a result of XPS analysis, a graphitized CNT yarn treated with mixed acid did not contain the functional groups. On the other hand, a graphitized CNT yarn treated with hot mixed acid (90°C) contained the functional groups. Crystallinity of this yarn was 4.5 times higher than the as-received CNT yarn. In addition, as a result of single fiber tensile tests, tensile strength of this yarn was increased by 79 % and Young’s modulus was increased by 173 % compared to the as-received CNT yarn.
{"title":"Functionalization and strengthening of graphitized untwisted carbon nanotube yarn with hot mixed acid treatment","authors":"K. Okumo, Y. Takahashi, Tae Sung Kim, Hidefumi Nikawa, A. Hosoi, H. Kawada","doi":"10.1299/TRANSJSME.19-00029","DOIUrl":"https://doi.org/10.1299/TRANSJSME.19-00029","url":null,"abstract":"Carbon nanotubes (CNT) have remarkable mechanical properties and low density. Since length of the CNT is limited, CNT yarn is regarded as a reinforced fiber of carbon fiber reinforced plastics. However, the CNT yarn does not have remarkable mechanical properties such as the individual CNT. The most popular way for improving the mechanical properties of the CNT yarn is to make composites with polymer such as polyvinyl alcohol or polyimide. If some functional groups such as carboxyl groups are introduced on the surface of CNTs, interaction between the CNTs and the polymer is improved and high mechanical properties will be obtained. In this study, untwisted CNT yarns were prepared by drawing vertical aligned CNTs through a die and functionalized with mixed acid. Mixed acid introduced not only the functional groups but also defects on the surface of CNTs. For reducing the defects, the CNT yarn was graphitized at a temperature of 2800°C before the mixed acid treatment. By the graphitization treatment, crystallinity of the CNT yarn was improved and amorphous carbon was removed. As a result of XPS analysis, a graphitized CNT yarn treated with mixed acid did not contain the functional groups. On the other hand, a graphitized CNT yarn treated with hot mixed acid (90°C) contained the functional groups. Crystallinity of this yarn was 4.5 times higher than the as-received CNT yarn. In addition, as a result of single fiber tensile tests, tensile strength of this yarn was increased by 79 % and Young’s modulus was increased by 173 % compared to the as-received CNT yarn.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"405 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121634814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1299/jsmemmt.2019.13.b21
M. Miyoshi, Shixian Liu, A. Okada, Akihito Hoshima, Masatoshi Kuita
Demand for high precision machining of complicated shapes has recently increased with the miniaturization of mechanical and electronic products. Therefore, further development of fine wire electrical discharge machining (EDM) technology using a thin wire electrode has been also requested. However, there might be a limit in improving the machining performance of fine wire EDM using conventional wire only by optimizing discharge pulse conditions and gap control. Therefore, it is essential to develop a new type of thin wire electrode for further improvement of wire EDM performance. In this study, high-zinc-content brass (γ-phase brass) coated steel core wire as a new type wire electrode was trially made to improve the machining stability. In wire EDM, zinc content of wire surface would contribute to rapidly cool down the gap by the evaporation due to its low boiling point. However, the surface of γ-phase brass coated wire tends to become rough in the heat treatment process of the wire. Thus, another type of the γ-phase brass coated wire with smoothed surface was also made by an extra finish drawing. The wire EDM characteristics using these wires were compared with those using conventional brass coated steel wire. Furthermore, the distribution of spark locations during process was evaluated by high-speed observation to investigate the influence of γphase brass and the surface roughness of wire. As a result, the cutting speed using the γ-phase brass coated steel wire with smoothed surface is faster than that using conventional wire because of uniform distribution of spark location.
{"title":"Fundamental study on fine wire EDM characteristics using γ-phase brass coated steel wire","authors":"M. Miyoshi, Shixian Liu, A. Okada, Akihito Hoshima, Masatoshi Kuita","doi":"10.1299/jsmemmt.2019.13.b21","DOIUrl":"https://doi.org/10.1299/jsmemmt.2019.13.b21","url":null,"abstract":"Demand for high precision machining of complicated shapes has recently increased with the miniaturization of mechanical and electronic products. Therefore, further development of fine wire electrical discharge machining (EDM) technology using a thin wire electrode has been also requested. However, there might be a limit in improving the machining performance of fine wire EDM using conventional wire only by optimizing discharge pulse conditions and gap control. Therefore, it is essential to develop a new type of thin wire electrode for further improvement of wire EDM performance. In this study, high-zinc-content brass (γ-phase brass) coated steel core wire as a new type wire electrode was trially made to improve the machining stability. In wire EDM, zinc content of wire surface would contribute to rapidly cool down the gap by the evaporation due to its low boiling point. However, the surface of γ-phase brass coated wire tends to become rough in the heat treatment process of the wire. Thus, another type of the γ-phase brass coated wire with smoothed surface was also made by an extra finish drawing. The wire EDM characteristics using these wires were compared with those using conventional brass coated steel wire. Furthermore, the distribution of spark locations during process was evaluated by high-speed observation to investigate the influence of γphase brass and the surface roughness of wire. As a result, the cutting speed using the γ-phase brass coated steel wire with smoothed surface is faster than that using conventional wire because of uniform distribution of spark location.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"214 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116160153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1299/TRANSJSME.18-00098
Koki Jimbo, T. Tateno
In this work, lattice structures appropriate for Additive Manufacturing (AM) are discussed and designed. By using AM, it becomes easy to realize original arbitral mechanical properties, in terms of anisotropy, vibration characteristic, light weight, and so on, by creating objects which have lattice structures inside their bodies. However, since the internal structures are very small, the influence of fabrication conditions such as deposition direction, nozzle diameter, and layer thickness is large. When the size of the cell strut diameter with respect to the nozzle diameter is relatively small, the shape of the struts becomes rough. In this study, the body-centered cubic (BCC) structure fabricated with ABS resign is chosen as a target lattice structure. BCC structure can reduce anisotropic properties due to the AM process. Specimens having different sizes of the same lattice cell structure are modeled by 3D-CAD. These specimens are fabricated by fused filament manufacturing (FFM) process, and tensile strength is examined. After the effect of the deposition direction and the nozzle path on mechanical strength of lattice cell structures was revealed, a design method for isotropic-tensile-strength structures was proposed. By scaling the size of BCC, isotropic-tensile-strength lattice structure was designed and specimens having the structure was fabricated by FFM process. Tensile strength test results showed the isotropy of tensile strength.
{"title":"Design of isotropic-tensile-strength lattice structure fabricated by AM","authors":"Koki Jimbo, T. Tateno","doi":"10.1299/TRANSJSME.18-00098","DOIUrl":"https://doi.org/10.1299/TRANSJSME.18-00098","url":null,"abstract":"In this work, lattice structures appropriate for Additive Manufacturing (AM) are discussed and designed. By using AM, it becomes easy to realize original arbitral mechanical properties, in terms of anisotropy, vibration characteristic, light weight, and so on, by creating objects which have lattice structures inside their bodies. However, since the internal structures are very small, the influence of fabrication conditions such as deposition direction, nozzle diameter, and layer thickness is large. When the size of the cell strut diameter with respect to the nozzle diameter is relatively small, the shape of the struts becomes rough. In this study, the body-centered cubic (BCC) structure fabricated with ABS resign is chosen as a target lattice structure. BCC structure can reduce anisotropic properties due to the AM process. Specimens having different sizes of the same lattice cell structure are modeled by 3D-CAD. These specimens are fabricated by fused filament manufacturing (FFM) process, and tensile strength is examined. After the effect of the deposition direction and the nozzle path on mechanical strength of lattice cell structures was revealed, a design method for isotropic-tensile-strength structures was proposed. By scaling the size of BCC, isotropic-tensile-strength lattice structure was designed and specimens having the structure was fabricated by FFM process. Tensile strength test results showed the isotropy of tensile strength.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"14 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115634701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1299/transjsme.20-00080
M. Yoneda, Kanji Fukuda, M. Ikebuchi, Y. Inoue, Michimasa Oi, A. Mitsuhashi, Atsushi Nishida, Masahiro Matsuda, M. Murakami, M. Itokazu
The purpose of this study is to investigate the gait improvement for lame patients based on the gait quality index estimated by the spectral analysis results of trunk acceleration. The gait quality index (GQI) is defined as the power spectrum ratio of the total value up to 10 Hz to that of the fw component in the vertical direction where fw is the pace frequency. The hemiplegic patients, patients after total hip arthroplasty, patients with femoral fractures, patient with anterior cruciate ligament injury and Parkinson's disease patients were selected in this study. Dynamic load factor (DLF) corresponding to the vertical walking force is also calculated using power spectrum density for time history trunk signals measured by the accelerometers. When the correlation between DLF and GQI was plotted, it was found that the gait quality index GQI was clearly improved (numerically reduced) for all lame patients as the increase of DLF due to the improvement of the gait. Based on these results, it was confirmed that the value of GQI in the vertical direction was the useful index in order to evaluate the gait improvement for all lame patients.
{"title":"Gait quality evaluation by the spectral analysis results of trunk acceleration and gait analysis of lame patients based on the gait quality index","authors":"M. Yoneda, Kanji Fukuda, M. Ikebuchi, Y. Inoue, Michimasa Oi, A. Mitsuhashi, Atsushi Nishida, Masahiro Matsuda, M. Murakami, M. Itokazu","doi":"10.1299/transjsme.20-00080","DOIUrl":"https://doi.org/10.1299/transjsme.20-00080","url":null,"abstract":"The purpose of this study is to investigate the gait improvement for lame patients based on the gait quality index estimated by the spectral analysis results of trunk acceleration. The gait quality index (GQI) is defined as the power spectrum ratio of the total value up to 10 Hz to that of the fw component in the vertical direction where fw is the pace frequency. The hemiplegic patients, patients after total hip arthroplasty, patients with femoral fractures, patient with anterior cruciate ligament injury and Parkinson's disease patients were selected in this study. Dynamic load factor (DLF) corresponding to the vertical walking force is also calculated using power spectrum density for time history trunk signals measured by the accelerometers. When the correlation between DLF and GQI was plotted, it was found that the gait quality index GQI was clearly improved (numerically reduced) for all lame patients as the increase of DLF due to the improvement of the gait. Based on these results, it was confirmed that the value of GQI in the vertical direction was the useful index in order to evaluate the gait improvement for all lame patients.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"197 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115666762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1299/JSMEDMC.2018.343
Yu Nagashima, N. Iwatuki, I. Ikeda
When one rides a car on a gravel road, a noise due to collision of gravels rolled up by tires makes him uncomfortable. The collisions are assumed as random impacts with respect to mass, collision time, position, velocity, angle and so on. In order to probabilistically estimate the noise, the time history of impact force in the case where a force sensor on a rigid pendulum hits a peripherally clamped thin rectangular plate is precisely measured for various impact speeds, angles and positions. The vibration response and sound pressure radiating from the plate are then estimated with the measured impact forces based on RayleighRitz method and impulse response method. It was then revealed that the time history of impact force could be represented with a certain time function for any impact speeds, angles and positions and that the component of the impact force perpendicular to the plate determined the maximum of the impact force. The time history of impact force can also be approximated as a superposition of the extreme function and Gaussian function. The estimated vibration acceleration of the plate and sound pressure agree very well the measured values. The noise generated by random impacts was estimated probabilistically. It was found that the noise strongly depends on the natural vibration modes of the plate.
{"title":"Estimation of the noise generated by the random impacts on a thin plate","authors":"Yu Nagashima, N. Iwatuki, I. Ikeda","doi":"10.1299/JSMEDMC.2018.343","DOIUrl":"https://doi.org/10.1299/JSMEDMC.2018.343","url":null,"abstract":"When one rides a car on a gravel road, a noise due to collision of gravels rolled up by tires makes him uncomfortable. The collisions are assumed as random impacts with respect to mass, collision time, position, velocity, angle and so on. In order to probabilistically estimate the noise, the time history of impact force in the case where a force sensor on a rigid pendulum hits a peripherally clamped thin rectangular plate is precisely measured for various impact speeds, angles and positions. The vibration response and sound pressure radiating from the plate are then estimated with the measured impact forces based on RayleighRitz method and impulse response method. It was then revealed that the time history of impact force could be represented with a certain time function for any impact speeds, angles and positions and that the component of the impact force perpendicular to the plate determined the maximum of the impact force. The time history of impact force can also be approximated as a superposition of the extreme function and Gaussian function. The estimated vibration acceleration of the plate and sound pressure agree very well the measured values. The noise generated by random impacts was estimated probabilistically. It was found that the noise strongly depends on the natural vibration modes of the plate.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115711163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1299/transjsme.19-00287
T. Kogawa, Nao Ogasawara, D. Mori, T. Akagaki
The PEEK material has been applied to a sliding bearing system in a power plant system because of its high mechanical durability. In the solid friction of the PEEK materials, the frictional heat becomes the important factor because the temperature increasing due to the frictional heat causes the rapidly increasing of the frictional coefficient of the specimen. In order to maintain the low frictional coefficient of the PEEK materials, the effective cooling method for the PEEK materials needs to be developed. In this study, the passive cooling method, which attaches the heat sink to the PEEK materials, was suggested. For evaluating the suggested cooling method of the PEEK materials, the calculation model adopting OpenFOAM, which is the open source software, has been developed. Adopting some functions and library of OpenFOAM, the frictional heat, heat resistance, and heat transfer coefficient on the heat sink were modeled. The sliding bearing experiment was conducted and time variation of the temperature and friction coefficient in the ring specimen were measured. The temperature variation in the ring specimen was compared with the calculation result. From the numerical calculation results, the developed calculation model could simulate the temperature time variation of the ring obtained in the experiment, when variation of the frictional coefficient, heat resistance, and heat transfer coefficient were modeled appropriately. Finally, the calculation predict ability using OpenFOAM in the considered situation was evaluated.
{"title":"Effects of heat sink on frictional heat effect in PEEK/Steel Pair（Numerical calculation using OpenFOAM model and experiments）","authors":"T. Kogawa, Nao Ogasawara, D. Mori, T. Akagaki","doi":"10.1299/transjsme.19-00287","DOIUrl":"https://doi.org/10.1299/transjsme.19-00287","url":null,"abstract":"The PEEK material has been applied to a sliding bearing system in a power plant system because of its high mechanical durability. In the solid friction of the PEEK materials, the frictional heat becomes the important factor because the temperature increasing due to the frictional heat causes the rapidly increasing of the frictional coefficient of the specimen. In order to maintain the low frictional coefficient of the PEEK materials, the effective cooling method for the PEEK materials needs to be developed. In this study, the passive cooling method, which attaches the heat sink to the PEEK materials, was suggested. For evaluating the suggested cooling method of the PEEK materials, the calculation model adopting OpenFOAM, which is the open source software, has been developed. Adopting some functions and library of OpenFOAM, the frictional heat, heat resistance, and heat transfer coefficient on the heat sink were modeled. The sliding bearing experiment was conducted and time variation of the temperature and friction coefficient in the ring specimen were measured. The temperature variation in the ring specimen was compared with the calculation result. From the numerical calculation results, the developed calculation model could simulate the temperature time variation of the ring obtained in the experiment, when variation of the frictional coefficient, heat resistance, and heat transfer coefficient were modeled appropriately. Finally, the calculation predict ability using OpenFOAM in the considered situation was evaluated.","PeriodicalId":341040,"journal":{"name":"Transactions of the JSME (in Japanese)","volume":"28 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123110385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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